Watch List notes:

NGC AU58 | Charles II (1660-1685), 'Royal African Company' Five-Guineas, 1676 VICESIMO OCTAVO, Elephant and Castle, first laureate head right, shorter ties, E&C below, rev. crowned shields cruciform, emblem-adorned sceptres in angles, edge lettering downwards, 41.65g [644.4grns], 6h (MCE 14; Schneider II, 425; EGC 183 [R4]; Duveen 89; King 99; Spink 3330), a small flaw on laurel wreath and light flecking in otherwise lustrous fields, a most imposing example of this sought-after Carolean trophy series, a pleasingly good very fine, the date seldom encountered at auction, especially in this impressive state, in NGC 'St Helier' holder, graded AU58 (Cert. #6769435-001).
Provenance
The St. Helier Collection of English Gold Coins,
Spink, by private treaty, February 1966,
Glendining, 27 November 1963, lot 122 - "extremely fine and very rare" - £800.0.0 [L. Davidson]
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For comparison, the Spink Numismatic Circular was listing Charles II Five Guineas in 'fine condition' at £225.0.0 in June 1965. The differential was once four times, whereas now it is between ten and twenty times between entry level and exalted specimens in the present marketplace.
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https://www.ngccoin.uk/certlookup/6769435-001/58/

Estimate: £30000 - £40000